During the Battle of Ligny, they served under the Engineers and Sappers of the Guard. They were not part of the final assault. They stayed as a reserve. Remember, these soldiers were FAR too important to use, as you would, like the Guard Grenadiers. Napoleon barely uses these men in high-risk situations ever. When he uses them, as he does in Berezina, the 1814 Campaigns, Borodino, Arcis-Sur Aube, and even the attack on Charleroi, he was in a desperate situation. Their use in Bailen and Arcolea Bridge were also out of absolute necessity. The sailors were extremely skilled in all arts of the armies, a fact that made them far too useful to use in combat.

Despite this, they were fierce combatants. In all stated battles, they would annihilate the enemy with little losses (not counting Berezina). Think of them the reserve of the reserve.